> How exactly would you ask this in an interview setting?

You now know which companies do this.

Every company laying off now has to wear a Scarlett Letter: "we're a layoffs company".

"Why is this role open"?

Either they will answer directly with something solid like "We're growing the team" or they will evade it which is still a meaningful answer for you. You could probe further with questions like:

"How has the team's headcount changed over the last 18-24 months?"

Basically you're alluding to 'employee turnover' without saying it.